I use rangefinders and SLRs. Either works well with 28 and 35mm lenses.
I use 28mm and 35mm Nikon wide-angle lenses. With these lenses, I have never had problems with barreling.
I have used Olympus cameras and lenses but I have never used the Olympus OM. The Olympus is capable of producing images that are equal in quality to those produced by Nikon.
I have also used M42 screw-mount wide-angle lenses made by Pentax, Fuji, and Vivitar. They also produce images of high quality.
Bottom line: barrel distortion is not a “huge deal” with these lenses. I have, however, had problems with barrel distortion from some bargain-priced wide-angle zoom lenses.